1. Field of the Invention
An embodiment of the present invention relates to a DNS (Domain Name System) system, medium, and method updating server address information, and more particularly to a system, medium, and method recording a network address of a DNS that has previously obtained server address information in a notification list, such that when the server address information changes the changed server address information is transmitted to the DNS to update the server address information recorded in the notification list. Thus, server address information stored by a DNS can be updated in real time, without necessarily requiring the use a TTL (Time To Live).
2. Description of the Related Art
Recently, due to the development of the Internet, IP (Internet Protocol) addresses have been allocated and used in nearly every terminal and every server, in order to connect with various web services, such web servers, e-mail servers, and the like, providing a user terminal with various services. However, since an IP address may be made up of many digits, it is typically not easy for a user to recognize and use all the digits of an IP address. Accordingly, users utilize domain names in their user terminals, with the domain names corresponding to a particular IP address. A DNS has been used for translating the domain names into corresponding IP addresses. Normally, a DNS includes a distributed database having a hierarchical name configuration with each client server model utilizing the distributed database for hierarchical communication.
FIG. 1 illustrates a conventional DNS system operation.
First, when a user wants to connect to a first server 105, e.g., corresponding to a domain “novel.book.com” through a user terminal, the user terminal requests, from a first DNS 101, the actual IP address corresponding to the domain “novel.book.com” via a DNS client program.
Upon the request, the first DNS 101 further requests from “root DNS” 102 for an IP address of “corn DNS” 103, managing a domain of a “.com”, in order to determine the IP address corresponding to the domain of a “novel.book.com,” in operation S101. Thereafter, “root DNS” 102 transmits the IP address “1.2.3.5” of the “com DNS” to the first DNS 101 after referring to a database 106 of the “root DNS” 102 for the IP address of the “corn DNS”. In this instance, the IP address “1.2.3.4” of the “root DNS” 102, used to contact the “root DNS” 102, may be recorded in a predetermined storage unit 109 included in the first DNS 101, for example.
Second, in operation S102, the first DNS 101 requests from the “corn DNS” 103 for an IP address of a “book DNS” 104 managing a domain of “book.com”. The “corn DNS” 103 transmits the IP address “1.2.3.6” of the “book DNS” to the first DNS 101 after referring to a database 107 of the “corn DNS” 103 for the IP address of the “book DNS”.
Finally, the first DNS 101 queries the “book DNS” 104 for the IP address of “novel.book.com,” in an operation S103, which transmits the IP address of “1.2.3.7” corresponding to the “novel.book.com” after referring to a database 108.
The first DNS 101 then transmits the IP address “1.2.3.7”, corresponding to the IP address of “novel.book.com”, to the user terminal. The user terminal may then connect to a host server 105 corresponding to the IP address “1.2.3.7”, in operation S104.
However, whenever a user terminal requests an IP address corresponding to a domain, the first DNS 101 stores the IP address corresponding to the domain in the storage unit 109, and also stores a TTL value, as defined in the DNS 104, in the storage unit 109, this repeatedly executing of the operations S101 to S103 may become a load on the first DNS 101.
After the period of time of the TTL passes, the first DNS server 101 will update the IP address corresponding to the domain when the IP address corresponding to the “novel.book.com” is requested, by repeating the execution of the operations S101 to S103.
However, when the IP address corresponding to the domain changes before the passage of the TTL period, the IP address maintained in the first DNS 101 will contain an invalid IP address, as it hasn't been updated. Therefore the IP address provided to a user terminal, from the first DNS 101, will also be invalid, resulting in a connection failure to the domain.
Consequently, to solve the above described problems, the inventors have found a need for the development of an operation of a DNS which may update a stored IP address corresponding to a domain in real time, thereby avoiding the above problems when the IP address changes and preventing connection failures.